Ehrlich K C, Montalbano B G, Cary J W
Southern Regional Research Center, USDA, PO Box 19687, New Orleans, LA 70179, USA.
Gene. 1999 Apr 16;230(2):249-57. doi: 10.1016/s0378-1119(99)00075-x.
AFLR is a Zn2Cys6-type sequence-specific DNA-binding protein that is thought to be necessary for expression of most of the genes in the aflatoxin pathway gene cluster in Aspergillus parasiticus and A. flavus, and the sterigmatocystin gene cluster in A. nidulans. However, it was not known whether AFLR bound to the promoter regions of each of the genes in the cluster. Recently, A. nidulans AFLR was shown to bind to the motif 5'-TCGN5CGA-3'. In the present study, we examined the binding of AFLR to promoter regions of 11 genes in the A. parasiticus cluster. Based on electrophoretic mobility shift assays, the genes nor1, pksA, adhA, norA, ver1, omtA, ordA, and, vbs, had at least one 5'-TCGN5CGA-3' binding site within 200bp of the translation start site, and pksA and ver1 had an additional binding site further upstream. Although the promoter region of avnA lacked this motif, AFLR bound weakly to the sequence 5'-TCGCAGCCCGG-3' at -110bp. One region in the promoter of the divergently transcribed genes aflR/aflJ bound weakly to AFLR even though it contained a site with at most only 7bp of the 5'-TCGN5CGA-3' motif. This partial site may be recognized by a monomeric form of AFLR. Based on a comparison of 16 possible sites, the preferred binding sequence was 5'-TCGSWNNSCGR-3'.
AFLR是一种Zn2Cys6型序列特异性DNA结合蛋白，被认为是寄生曲霉和黄曲霉中黄曲霉毒素途径基因簇以及构巢曲霉中柄曲霉素基因簇中大多数基因表达所必需的。然而，尚不清楚AFLR是否与该基因簇中每个基因的启动子区域结合。最近，已证明构巢曲霉AFLR与基序5'-TCGN5CGA-3'结合。在本研究中，我们检测了AFLR与寄生曲霉基因簇中11个基因的启动子区域的结合情况。基于电泳迁移率变动分析，基因nor1、pksA、adhA、norA、ver1、omtA、ordA和vbs在翻译起始位点200bp内至少有一个5'-TCGN5CGA-3'结合位点，pksA和ver1在更上游还有一个额外的结合位点。尽管avnA的启动子区域缺乏该基序，但AFLR与-110bp处的序列5'-TCGCAGCCCGG-3'弱结合。反向转录基因aflR/aflJ启动子中的一个区域与AFLR弱结合，尽管它包含一个最多只有7bp的5'-TCGN5CGA-3'基序的位点。这个部分位点可能被AFLR的单体形式识别。基于对16个可能位点的比较，优选的结合序列是5'-TCGSWNNSCGR-3'。
